It’s first period at Harlem’s Cristo Rey high school, a private Catholic school for motivated low-income kids. In a third floor classroom, 10 sophomores and juniors stare into their wide Apple monitors and puzzle over what line of code they need to add to their rudimentary computer programs in order to make their names appear in a gray block between the word “’Welcome” and an exclamation point.

Their teacher, Kevin Mitchell, 29, is a software engineer and volunteer at the tiny nonprofit startup, ScriptEd, which provides coding instruction in underserved high schools in New York City. Mitchell, a calm figure with an easy smile, suggests his students write a line of code: a word bookended by some simple punctuation. The students diligently attempt to implement it on their own.

For some, the code works on the first try. Welcome Jorge! Welcome Sonya! Around the room, a few other students make low groans—unexpected results. “Did you forget your curly brackets,” queries Mitchell, referring to the punctuation that looks like this “}” Other students have gotten no results at all.

Byron Acosta, a junior at Cristo Rey, seems satisfied when his name pops up. Before he took this class, Acosta says he didn’t know anyone with the skills he was learning in class. Even though he’s a self-described “English and history guy” he jumped at the chance to learn some basics. So far, he likes it. And he’s absorbed Mitchell’s Golden Rule: “You have to be specific in your language,” he offers. “One typo and you can mess everything up.”

Mitchell walks among the students, troubleshooting. Writing code is like giving commands, he tells the students. “The computer can’t know what you don’t tell it.”

To an observer, the class seems to move slowly but the students aren’t restless—they’re in a dynamic relationship with a technology, struggling to figure out who will come out on top.

It’s a battle that Maurya Couvares, co-founder of ScriptEd, and a lot of other savvy people, think more high school students will need to engage in. “Coding will be the key to innovation in the future but many students, but especially low-income students, aren’t exposed to it,” she says. Tech moguls including Bill Gates, Google’s Eric Schmidt and Meg Whitman from Hewlett-Packard agree with her. They’ve thrown their weight behind Code.org, a new nonprofit whose “learn to code” videos have gone viral. They say that coding, programming and computer science will be the language of the 21st century. "In a world that's increasingly run on technology, computer science is a liberal art that every student should be exposed to, regardless of their path in life,” says Code.org’s Hadi Partovi.

Labor economists say Partovi might be right. By 2020, the U.S Bureau of Labor Statistics is projecting that 778,000 computer jobs will be created. “That is substantial growth that is expected to outpace the growth of the overall economy,” says Martin Kohli, a chief regional economist there. Jan Cuny, who oversees the National Science Foundation’s CS10K initiative, a $40 million program aimed at getting more computer science teachers in high school classroom, says those projections are low. She estimates that 1.4 million jobs—and 60 percent of the STEM jobs of the future—will require computing skills.

They are good jobs too. In 2012, according to the BLS, the average salary for a computer programmer was about $80,000. (By comparison, the average wage for American workers is $45,800.)

But as the need for workers with computer science skills is exploding, the number of young people with those skills is actually dropping. According to a federal study of high school transcripts, 25 percent of high schoolers took a computer science class in 1999. In 2009, the last date for which this data is available, only 19 percent of high schoolers had learned to write code. Not surprisingly, the percentage of college freshmen who indicate they want to major in computing has declined by 70 percent over the last decade.

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